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Contributions to the nucleon form factors from bubble and tadpole diagrams
Z. Y. Gao, P. Wang, M. Y. Yang
Published:   , doi: 10.1088/1674-1137/aca466
Abstract:
The nonlocal chiral effective theory is applied to investigate the electromagnetic and strange form factors of nucleon. The bubble and tadpole diagrams are included in the calculation. With the contributions from bubble and tadpole diagrams, the obtained electromagnetic form factors are close to the results without these contributions as long as the low energy constants \begin{document}$ c_1 $\end{document} and \begin{document}$ c_2 $\end{document} are properly chosen, while the magnitudes of strange form factors become larger. The electromagnetic form factors are in good agreement with the experimental results, while the magnitudes of strange form factors are larger than the lattice data.
Search for Charm-quark Production via Dimuons in Neutrino Telescopes
ChuanLe Sun, Fuyudi Zhang, Fan Hu, Donglian Xu, Jun Gao
Published:   , doi: 10.1088/1674-1137/aca465
Abstract:
Dimuon events induced by charm-quark productions from neutrino deep inelastic scattering (DIS) processes have been studied in traditional DIS experiments for decades. The recent progress in neutrino telescopes makes it possible to search such dimuon events at energies far beyond laboratory scale. In this paper, we construct a simulation framework to calculate yields and distributions of dimuon signals in an IceCube-like km3 scale neutrino telescope. Due to experimental limitation in the resolution of double-track lateral distance, only dimuon produced outside the detector volume are considered. Detailed information about simulation results for ten years exposure is demonstrated. Both an earlier work [1] and our work study a similar situation, we therefore use that paper as a baseline to conduct comparisons. We then estimate the impacts of different calculation methods of muon energy losses. Finally, we study the experimental potential of dimuon searches under the hypothesis of single-muon background-only. Our results based on a simplified double-track reconstruction indicate a moderate sensitivity especially with the ORCA configuration. Further developments on both the reconstruction algorithm and possible detector designs are thus required, and are under investigation.
Gravitational decoupling for hairy black holes in asymptotic AdS spacetimes
Chao-Ming Zhang, Ming Zhang, De-Cheng Zou
Published:   , doi: 10.1088/1674-1137/ac9b2c
Abstract:
In this study, the gravitational decoupling approach via extended geometric deformation is utilized to generate analytical black hole solutions owing to its simplicity and effectiveness. Considering the external fields surrounding Schwarzschild AdS black holes, we derive hairy black hole solutions in asymptotic AdS spacetime, satisfying the strong and dominant energy conditions. Moreover, we find that if the black hole spacetime is a fluid system, the fluid under each of these conditions is anisotropic.
Effects from Hadronic Structure of Photon on $ {\boldsymbol B\boldsymbol\to\boldsymbol\phi\boldsymbol\gamma }$ and ${\boldsymbol B_{\boldsymbol s}\boldsymbol\to(\boldsymbol\rho^{\bf 0},\boldsymbol\omega)\gamma }$ Decays
Yun Li, Zhi-Tian Zou, Yue-Long Shen, Ying Li
Published:   , doi: 10.1088/1674-1137/aca38f
Abstract:
Using the perturbative QCD approach, we studied the effects from hadronic structure of photon on the pure annihilation rediative decays \begin{document}$ B\to\phi\gamma $\end{document} and \begin{document}$ B_s\to(\rho^0,\omega)\gamma $\end{document}. These decays have small branching fractions due to the power suppression by the \begin{document}$ \Lambda/m_B $\end{document}, which make them very sensitive to the next-leading power corrections. The quark components and the related two-particle distribution amplitudes of a final state photon are introduced. The branching fractions can be enhanced remarkably by the factorizable and nonfactorizable emission diagrams. The branching fraction of \begin{document}$ B\to \phi\gamma $\end{document} even increases by about 40 times, and those of \begin{document}$ B_s \to \rho^0\gamma $\end{document} and \begin{document}$ B_s \to \omega\gamma $\end{document} are at the order of \begin{document}$ {\cal O}(10^{-10}) $\end{document}. We also note that the ratio of branching fractions of \begin{document}$ B_s \to \rho^0\gamma $\end{document} and \begin{document}$ B_s \to \omega\gamma $\end{document} is very sensitive to the effects from hadronic structure of photon. All above results could be tested in future.
The neutron skin thickness of 90Zr and symmetry energy constrained by the charge exchange spin-dipole excitations
Shi-Hui Cheng, Jing Wen, Li-Gang Cao, Feng-Shou Zhang
Published:  
Abstract:
The charge exchange spin-dipole (SD) excitations of \begin{document}$ ^{90} $\end{document}Zr are studied in the Skyrme Hartee-Fock plus proton-neutron random phase approximation with SAMi-J interactions. Experimental value of the model-independent sum rule obtained from the SD strength distributions of \begin{document}$ ^{90} $\end{document}Zr(p,n)\begin{document}$ ^{90} $\end{document}Nb and \begin{document}$ ^{90} $\end{document}Zr(n,p)\begin{document}$ ^{90} $\end{document}Y is used to deduce the neutron skin thickness. The neutron skin thickness \begin{document}$ \Delta r_{np} $\end{document} of \begin{document}$ ^{90} $\end{document}Zr is extracted as \begin{document}$ 0.083\pm0.032 $\end{document} fm, which is similar to the results of other studies. Based on the correlation analysis of the neutron skin thickness \begin{document}$ \Delta r_{np} $\end{document} and the nuclear symmetry energy J as well as its slope parameter L, a constraint from the extracted \begin{document}$ \Delta r_{np} $\end{document} leads to the limitation of J to \begin{document}$ 29.2 \pm 2.6 $\end{document} MeV and L to \begin{document}$ 53.3 \pm 28.2 $\end{document} MeV.
The universal scaling of kinetic freeze-out parameters across different collision systems at the LHC energy
Lian Liu, Zhong-Bao Yin, Liang Zheng
Published:  
Abstract:
In this paper, we perform the Tsallis Blast-Wave analysis on the transverse momentum spectra of identified hadrons produced in a wide range of collision systems at the Large Hadron Collider (LHC) including pp, pPb, XeXe and PbPb collisions. The kinetic freeze-out properties are investigated across these systems varying with the event multiplicity. We find that the extracted kinetic freeze-out temperature, radial flow velocity and the non-extensive parameter exhibit a universal scaling behavior for these systems with very different geometric size, especially when the independent baryon Tsallis non-extensive parameter is considered. This universality may indicate the existence of a unified partonic evolution stage in different collision systems at the LHC energies.
Standard Model Effective Field Theory from On-shell Amplitudes
Teng Ma, Jing Shu, Ming-Lei Xiao
Published:   , doi: 10.1088/1674-1137/aca200
Abstract:
We present a general method of constructing unfactorizable on-shell amplitudes (amplitude basis), and build up their one-to-one correspondence to the independent and complete operator basis in effective field theory (EFT). We apply our method to the Standard Model EFT, and identify the amplitude basis in dimension 5 and 6, which correspond to the Weinberg operator and operators in Warsaw basis except for some linear combinations.
Impact of the New 12C+12C Reaction Rate on Presupernova Nucleosynthesis
Wenyu Xin, Ken’ichi Nomoto, Gang Zhao, Wenbo Wu
Published:   , doi: 10.1088/1674-1137/aca1ff
Abstract:
The 12C+12C reaction rate plays an essential role in stellar evolution and nucleosynthesis. Nevertheless, uncertainties of this reaction rate are still large. We calculated a series of stellar evolution models with the near solar abundance from the zero-age main-sequence through presupernova stages for the initial masses of 20 M\begin{document}$ _\odot $\end{document} to 40 M\begin{document}$ _\odot $\end{document}. The 12C+12C reaction rates from two different works are used in our work. One is the rate obtained with Trojan Horse Method (THM) by Tumino et al. [1] and the other is obtained by Mukhamedzhanov et al. [2] (Muk19). Then the comparisons of nucleosynthesis and presupernova isotopic abundances are conducted. In particular, we found that in the C burning shell the models with the THM produce a smaller amount of 23Na and some neutron-rich isotopes than Muk19. The difference in abundance ratios of Na/Mg, S/Mg, Ar/Mg and K/Mg between the two models are apparent. We compared Na/Mg obtained from our theoretical presupernovae models with Na/Mg in stellar atmospheres observed with high-resolution spectra as well as from the latest galactic chemical evolution model. Although Na/Mg obtained from THM is within 2σ of the observed stellar ratio, the theoretical uncertainty of Na/Mg introduced by the uncertainty of the 12C+12C reaction rate is almost equivalent to the standard deviation of astronomical observations. Therefore, a more accurate 12C+12C reaction rate is crucial.
Next-to-leading-order QCD corrections to gluon fragmentation into ${ {}^{\bf 1}{\boldsymbol S}_{\bf 0}^{\bf(1,8)} }$ quarkonia
Feng Feng, Yu Jia
Published:   , doi: 10.1088/1674-1137/aca1aa
Abstract:
Within the NRQCD factorization framework, we compute the next-to-leading-order QCD corrections to the gluon fragmentation into the \begin{document}$ {}^1S_0^{(1,8)} $\end{document} Fock components of a quarkonium, at the lowest order in velocity expansion. We follow the operator definition of the fragmentation function advanced by Collins and Soper. The key technique underpinning our calculation is the sector decomposition method widely used in the area of multi-loop computation. It is found that the NLO QCD corrections have significant effects, and qualitatively modify the profiles of the corresponding leading-order fragmentation functions.
Cumulative Fission Yield Measurements with 14.7 MeV Neutrons on 238U
Xianlin Yang, Changlin Lan, Yangbo Nie, Liyang Jiang, Yijia Qiu, Yujie Ge, Hongtao Chen, Kai Zhang, Yuting Wei, Jiahao Wang, Gong Jiang, Xichao Ruan, Yi Yang
Published:   , doi: 10.1088/1674-1137/aca1ab
Abstract:
The fission yield data in 14 MeV energy neutron induced fission of 238U play an important role for decay heat calculation and for generation-IV reactor designs. In order to measure fission product yields (FPYs) of 238U induced by 14 MeV neutrons accurately, the cumulative yields of fission products ranging from 92Sr to 147Nd in 238U(n, f) with 14.7 MeV neutron have been determined using an off-line γ-ray spectrometric technique. The 14.7 MeV quasi-monoenergetic neutron beam was provided by K-400 D-T neutron generator at China Academy of Engineering Physics (CAEP). Fission products were measured by a low background high purity germanium gamma spectrometer. The neutron flux was obtained from 93Nb (n,2n)92mNb reaction, and the mean neutron energy was calculated by the cross-section ratios for the 90Zr(n,2n)89Zr and 93Nb(n,2n)92mNb reactions. With a series of corrections, high precision cumulative yields of 20 fission products were obtained. Our FPYs for 238U(n,f) reaction at 14.7 MeV were compared with the existing data at 14 MeV from Experimental Nuclear Reaction Data and Evaluated Nuclear Data, respectively. They are helpful to design of generation-IV reactor and the construction of evaluated fission yield database.
Singularities of regular black holes and the monodromy method for asymptotic quasinormal modes
Chen Lan, Yi-Fan Wang
Published:   , doi: 10.1088/1674-1137/aca07c
Abstract:
We used the monodromy method to investigate the asymptotic quasinormal modes of regular black holes based on the explicit Stokes portraits. We found that for regular black holes with spherical symmetry and a single shape function, the analytical forms of the asymptotic frequency spectrum are not universal and do not depend on the multipole number, but rather on the presence of complex singularities and the trajectory of asymptotic solutions along the Stokes lines.
${ \boldsymbol f(\bar{\boldsymbol R}, \boldsymbol L(\boldsymbol X))} $-gravity in the context of dark energy with power law expansion and energy conditions
Goutam Manna, Arijit Panda, Aninda Karmakar, Saibal Ray, Md. Rabiul Islam
Published:   , doi: 10.1088/1674-1137/ac9fbe
Abstract:
The motto of this work is to generate a general formalism of \begin{document}$ f(\bar{R}, L(X))- $\end{document}gravity in the context of dark energy under the framework of the K-essence emergent geometry with the Dirac-Born-Infeld (DBI) variety of action, where \begin{document}$ \bar{R} $\end{document} is the familiar Ricci scalar, \begin{document}$ L(X) $\end{document} is the DBI type non-canonical Lagrangian with \begin{document}$ X={1\over 2}g^{\mu\nu}\nabla_{\mu}\phi\nabla_{\nu}\phi $\end{document} and ϕ is the K-essence scalar field. The emergent gravity metric \begin{document}$ {\bar{G}}_{\mu\nu} $\end{document} and the well known gravitational metric \begin{document}$ g_{\mu\nu} $\end{document} are not conformally equivalent. We have constructed a modified field equation using the metric formalism in \begin{document}$ f(\bar{R}, L(X)) $\end{document}-gravity incorporating the corresponding Friedmann equations in the framework of the background gravitational metric which is of Friedmann-Lemaître-Robertson-Walker (FLRW) type. The solution of modified Friedmann equations have been deduced for the specific choice of \begin{document}$ f(\bar{R}, L(X)) $\end{document}, which is of Starobinsky-type, using power law expansion method. The consistency of the model with the accelerating phase of the Universe has been shown, when we restrict ourselves to consider the value of the dark energy density, as \begin{document}$ \dot\phi^{2}=\frac{8}{9}=0.888 <1 $\end{document}, which indicates that the present Universe is dark energy dominated. Graphical plots for the energy density (ρ), pressure (p) and equation of state parameter (\begin{document}$ {\omega} $\end{document}) w.r.t. time (t) based on parametric values are interestingly consistent with the dark energy domination and hence accelerating features. We also put some light on the corresponding energy conditions and constraints of the \begin{document}$ f(\bar{R}, L(X)) $\end{document} theory with one basic example.
A leptoquark and vector-like quark extended model for the simultaneous explanation of the W boson mass and muon g-2 anomalies
Shi-Ping He
Published:   , doi: 10.1088/1674-1137/ac9e4c
Abstract:
The CDF collaboration has announced a new measurement result of the W boson mass recently, and it is in tension with the standard model (SM) prediction. In this paper, we will explain this anomaly in the vector-like quark (VLQ) \begin{document}$ (X,T,B)_{L,R} $\end{document} and leptoquark (LQ) \begin{document}$ S_3 $\end{document} extended model. In this model, both the VLQ and LQ have positive corrections to the W boson mass. Besides, it can also be a solution to the \begin{document}$ (g-2)_{\mu} $\end{document} anomaly because of the chiral enhancements from top, T, and B quarks.
Weak deflection angle and shadow cast by the charged-Kiselev black hole with cloud of strings in plasma
Farruh Atamurotov, Ibrar Hussain, Ghulam Mustafa, Ali Övgün
Published:   , doi: 10.1088/1674-1137/ac9fbb
Abstract:
In this work, the gravitational deflection angle of photon in the weak field limit (or the weak deflection angle) and shadow cast by the electrically charged and spherically symmetric static Kiselev black hole (BH) in the string cloud background are investigated. The influence of the BH charge Q, the quintessential parameter γ and the string cloud parameter a is studied on the weak deflection angle using the Gauss-Bonnet theorem, on the radius of photon spheres and on the size of the BH shadow in the spacetime geometry of the charged-Kiselev BH in string clouds. Moreover, we study the effects of plasma (uniform and non-uniform) on the weak deflection angle and on the shadow cast by the charged-Kiselev BH surrounded by the clouds of strings. In the presence of uniform/nonuniform plasma medium, increase in the cloud of string parameter a, increases the deflection angle α. On the other hand decrease in the BH charge Q, decreases the deflection angle. Further we observe that an increase of the BH charge Q causes a decrease in the size of the shadow of the BH. We notice that with increase in the values of the parameters γ and a, the size of the BH shadow also increases and therefore the intensity of the gravitational field around the charged-Kiselev BH in string clouds increases. Thus the gravitational field of the charged-Kiselev BH in string cloud background would be stronger than the field produced by the pure Reissner-Nordstrom BH. Moreover, we use the data released by the Event Horizon Telescope (EHT) collaboration, for the supermassive BHs M87* and Sgr A*, to obtain constraints on the values of the parameters γ and a.
Relativistic correction to the dissociation temperature of Bc mesons in the hot medium
Guangyu Li, Baoyi Chen, Yunpeng Liu
Published:   , doi: 10.1088/1674-1137/ac9fbd
Abstract:
By solving two body Dirac equations with potentials at finite temperature, we calculated the dissociation temperature \begin{document}$ T_d $\end{document} of \begin{document}$ B_c $\end{document} mesons in the quark-gluon plasma. It is found that the \begin{document}$ T_d $\end{document} becomes higher with the relativistic correction than the \begin{document}$ T_d $\end{document} from the Schrödinger equation. Both the short range interaction and the constant term of the potential at the long-range scale have a contribution to the shift of \begin{document}$ T_d $\end{document}, while the spin interaction is negligible.
Chaos bound in Kerr-Newman-Taub-NUT black holes via circular motions
Deyou Chen, Chuanhong Gao
Published:   , doi: 10.1088/1674-1137/ac9fb9
Abstract:
In this paper, we investigate the influence of the angular momentum of a charged particle around Kerr-Newman-Taub-NUT black holes on the Lyapunov exponent, and find spatial regions where the chaos bound is violated. The exponent is obtained by solving the determination of eigenvalues of a Jacobian matrix in the phase space. Equilibrium positions are obtained by fixing the charge-to-mass ratio of the particle and changing its angular momentum. For certain values of the black holes' electric charge, NUT charge and rotational parameter, a small angular momentum of the particle, even if zero angular momentum, causes the violation of the bound. This violation disappears at a certain distance from the event horizon of the non-extremal Kerr-Newman-Taub-NUT black hole when the angular momentum increases to a certain value. When the black hole is extremal, the violation always exists no matter how the angular momentum changes. The ranges of the angular momentum and spatial regions for the violation are found. The black holes and particle rotating in the same direction and in the opposite directions are discussed.
The effect of nonlinear electrodynamics on shadows of slowly rotating black holes
Jiuyang Tang, Yunqi Liu, Wei-Liang Qian, Ruihong Yue
Published:   , doi: 10.1088/1674-1137/ac9fba
Abstract:
The cross-sections of 238U (n, γ) 239U reaction in 3.0-7.0 MeV energy region measured by relative activation method
Chun Wen, Zheng Han, Xiao-Bing Luo
Published:   , doi: 10.1088/1674-1137/ac9e9b
Abstract:
The reaction cross-sections of 238U (n, γ)239U have been experimentally determined at the neutron energies of 6.117 ± 0.119 MeV, 4.626 ± 0.086 MeV and 3.622 ± 0.348 MeV employing the relative activation approach along with off-line γ-rays spectroscopy method. The D (d, n)3He reaction was utilized to obtain monoenergetic neutrons of the required energy and the 197Au (n, γ)198Au reaction cross-sections were adopted as the referential standard to ascertain the neutron capture cross-sections of 238U. Furthermore, the effects of low-energy scattered neutrons, neutron fluence fluctuation, the counting geometric corrections when measuring γ-rays, neutrons and γ-rays self-absorption caused by samples thickness have been considered and revised in the present work. For comparison with experimental results, the cross-sections of 238U (n, γ)239U reaction were calculated theoretically with original parametric TALYS-1.9 program. The experimental measurements were also in contrast with previous experimental results and the evaluation data available for ROSFOND-2010, CENDL-3.2 and ENDF/B-VIII.0.
Possibility of experimental study on nonleptonic $ B_{c}^{\ast} $ weak decays
Yueling Yang, Liting Wang, Jinshu Huang, Qin Chang, Junfeng Sun
Published:   , doi: 10.1088/1674-1137/aca00d
Abstract:
The ground vector \begin{document}$ B_{c}^{\ast} $\end{document} meson has not yet been experimentally discovered until now. Besides the dominant electromagnetic decays, nonleptonic weak decays provide another choice to search for the mysterious \begin{document}$ B_{c}^{\ast} $\end{document} mesons. Inspired by the potential prospects of \begin{document}$ B_{c}^{\ast} $\end{document} meson in the future high-luminosity colliders, nonleptonic \begin{document}$ B_{c}^{\ast} $\end{document} weak decays induced by bottom and charm quark decays are studied within SM by using naive factorization approach. It is found that for \begin{document}$ B_{c}^{\ast} $\end{document} \begin{document}$ {\to} $\end{document} \begin{document}$ B_{s,d}{\pi} $\end{document}, \begin{document}$ B_{s,d}^{\ast}{\pi} $\end{document}, \begin{document}$ B_{s,d}{\rho} $\end{document}, \begin{document}$ B_{s}K $\end{document}, \begin{document}$ B_{s}^{\ast}K $\end{document}, \begin{document}$ B_{s}K^{\ast} $\end{document}, \begin{document}$ {\eta}_{c}(1S,2S){\pi} $\end{document}, \begin{document}$ {\eta}_{c}(1S,2S){\rho} $\end{document} and \begin{document}$ {\psi}(1S,2S){\pi} $\end{document} decays, a few hundred and even thousand of events might be observable at CEPC, FCC-ee and LHCb@HL-LHC experiments.
Signals of α clusters in 16O+16O collisions at LHC from relativistic hydrodynamic simulations
Chi Ding, Long-Gang Pang, Song Zhang, Yu-Gang Ma
Published:   , doi: 10.1088/1674-1137/ac9fb8
Abstract:
In relativistic heavy ion collisions, the fluctuations of initial entropy density convert to correlations of final state hadrons in momentum space, through collective expansion of the strongly interacting QCD matter. We ask by using a (3+1)D viscous hydrodynamic program CLVisc whether the nuclear structure, which provides initial state fluctuations as well as correlations, can affect the final state of heavy ion collisions, whether one can find signals of α cluster structure in oxygen using the final state observables in \begin{document}$ ^{16}\text{O}+{}^{16}\text{O} $\end{document} collisions at the CERN Large Hadron Collider (LHC). For the initial nucleon distributions in oxygen nuclei, we have compared 3 different configurations, the tetrahedral structure with four-α clusters, the deformed Woods-Saxon distribution as well as a spherical symmetric Woods-Saxon distribution. Our results show that the charged multiplicity as a function of centrality and the elliptic flow at most central collisions using 4-α structure differs from Woods-Saxon and deformed Woods-Saxon distributions, which may help to identify the α clustering structures in oxygen nuclei.
Proposal for a Nuclear Light Source
E. V. Tkalya, P. V. Borisyuk, M. S. Domashenko, Yu. Yu. Lebedinskii
Published:   , doi: 10.1088/1674-1137/ac9f0a
Abstract:
The paper considers a principal possibility of creating a nuclear light source of the vacuum ultra violet (VUV) range based on the \begin{document}$ ^{229} $\end{document}Th nucleus. This nuclear light source can help to solve two main problems — excitation of the low-lying \begin{document}$ ^{229m} $\end{document}Th isomer and precision measurement of the nuclear isomeric transition energy. The Thorium nuclear light source is based on the nuclei implanted in a thin dielectric film with a large bandgap. While passing an electric current through the sample, the \begin{document}$ ^{229} $\end{document}Th nuclei are excited to the low energy isomeric state \begin{document}$ 3/2^+(8.19\pm0.12 $\end{document} eV) in the process of inelastic scattering of conduction electrons. The subsequent spontaneous decay of \begin{document}$ ^{229m} $\end{document}Th is followed by the emission of γ quanta in the VUV range. The luminosity of the Thorium nuclear light source is approximately \begin{document}$ 10^5 $\end{document} photons/s per 1 A of current and per 1 ng of \begin{document}$ ^{229} $\end{document}Th. The suggested scheme to obtain γ radiation from the \begin{document}$ ^{229m} $\end{document}Th isomer can be considered as a kind of nuclear analogue of the optical radiation from the usual metal-insulator-semiconductor (MIS) junction.
α-cluster decay from 24Mg resonances produced in 12C(16O,24Mg)α reaction
Dong-Xi Wang, Yan-Lin Ye, Cheng-Jian Lin, Jia-Hao Chen, Kai Ma, Jia-Xing Han, Hui-Ming Jia, Lei Yang, Li-Sheng Yang, Zi-Yao Hu, Ying Chen, Wei-Liang Pu, Gen Li, Zhi-Wei Tan, Hong-Yu Zhu, Tian-Peng Luo, Shan-Hao Zhong, Da-Hu Huang, Jian-Ling Lou, Xiao-Fei Yang, Qi-Te Li, Jin-Yan Xu, Zai-Hong Yang, Kang Wei
Published:   , doi: 10.1088/1674-1137/ac9e9a
Abstract:
An α-transfer and cluster-decay experiment, \begin{document}$ ^{12} $\end{document}C(\begin{document}$ ^{16} $\end{document}O,\begin{document}$ ^{24} $\end{document}Mg\begin{document}$ \rightarrow $\end{document}α+\begin{document}$ ^{20} $\end{document}Ne)α, was performed at a beam energy of 96 MeV. Both the recoil and the decay α particles were detected in coincidence, allowing to deduce the energy-momentum of \begin{document}$ ^{20} $\end{document}Ne fragment. A number of resonant states of \begin{document}$ ^{24} $\end{document}Mg are reconstructed up to an excitation energy of about 30 MeV. Owing to the experimentally achieved excellent resolutions on Q-value and excitation-energy spectra, the relative decay widths for each resonant state in \begin{document}$ ^{24} $\end{document}Mg to various final states of \begin{document}$ ^{20} $\end{document}Ne have been extracted, together with the total decay width. The obtained results provide a good test ground for theoretical descriptions of the multiple clustering configurations in \begin{document}$ ^{24} $\end{document}Mg.
Role of a high ground-state centrifugal barrier in the breakup of 31Ne nucleus
B. Mukeru
Published:   , doi: 10.1088/1674-1137/ac9e4b
Abstract:
An analysis of the breakup of the \begin{document}$ ^{31}{\rm Ne} $\end{document} weakly-bound neutron-halo system on a lead target is presented, considering \begin{document}$ 2p_{3/2} $\end{document} and \begin{document}$ 1f_{7/2} $\end{document} ground-state configurations. It is shown that a high centrifugal barrier almost wipes out the breakup channel, thus assimilating the breakup of a weakly-bound system to that of a tightly-bound system, and also reduces the range of the monopole nuclear potential. Consequently, a high centrifugal barrier prevents the suppression of the Coulomb-nuclear interference (CNI) peak by weakening couplings to the breakup channel and by reducing the range of the monopole nuclear potential, two main factors that would otherwise suppress such peak. In conclusion, the present study also identifies couplings to the breakup channel and a long-ranged monopole nuclear potential as the main factors that lead to the suppression of the CNI peak. A low centrifugal barrier together with a Coulomb barrier would as well effectively prevent the suppression of the CNI peak in proton-halos, as it has been reported in the case of the \begin{document}$ ^8{\rm B} $\end{document} proton-halo.
The Decay constants of Bc(nS) and Bc*(nS)
Chao Sun, Ru-Hui Ni, Muyang Chen
Published:   , doi: 10.1088/1674-1137/ac9dea
Abstract:
The decay constants of the low lying S-wave \begin{document}$ B_c $\end{document} mesons, i.e. \begin{document}$ B_c(nS) $\end{document} and \begin{document}$ B^*_c(nS) $\end{document} with \begin{document}$ n\leq 3 $\end{document}, are calculated in the nonrelativistic quark model. The running coupling of the strong interaction is taken into account, and the uncertainties due to varying parameters and losing Lorentz covariance are considered carefully. As a byproduct, the decay constants of the low lying S-wave charmonium and bottomium states are given in the appendixes.
Constraint of ξ-moments calculated with QCD sum rules on the pion distribution amplitude models
Tao Zhong, Zhi-Hao Zhu, Hai-Bing Fu
Published:  
Abstract:
So far, the behavior of the pionic leading-twist distribution amplitude (DA) \begin{document}$ \phi_{2;\pi}(x,\mu) $\end{document} \begin{document}$ - $\end{document} which is universal physical quantity and enters the high-energy processes involving pion based on the factorization theorem \begin{document}$ - $\end{document} has not been completely consistent. The form of \begin{document}$ \phi_{2;\pi}(x,\mu) $\end{document} is usually described by phenomenological models and constrained by the experimental data of the exclusive processes containing pion or the moments calculated with the QCD sum rules and lattice QCD theory. Obviously, an appropriate model is very important for us to determine the exact behavior of \begin{document}$ \phi_{2;\pi}(x,\mu) $\end{document}. In this paper, by adopting the least squares method to fit the ξ-moments calculated with QCD sum rules based on the background field theory, we perform an analysis for several commonly used models of the pionic leading-twist DA in the literature, such as the truncation form of the Gegenbauer polynomial series, the light-cone harmonic oscillator model, the form from the Dyson-Schwinger equations, the model from the light-front holographic AdS/QCD and a simple power-law parametrization form.
Double-heavy tetraquarks with strangeness in the chiral quark model
Xiaoyun Chen, Fu-Lai Wang, Yue Tan, Youchang Yang
Published:   , doi: 10.1088/1674-1137/ac9de9
Abstract:
Recently, some progresses have been made on the double-heavy tetraquarks in the experiments, such as \begin{document}$ T_{cc} $\end{document} reported by LHCb Collaboration, and \begin{document}$ X_{cc\bar{s}\bar{s}} $\end{document} reported by the Belle Collaboration. Coming on the heels of our previous work about \begin{document}$ T_{cc} $\end{document} and \begin{document}$ T_{bb} $\end{document}, we present a study on the bound states and the resonance states of its companions \begin{document}$ QQ\bar{q}\bar{s} $\end{document} (\begin{document}$ Q=c,b; q=u, s $\end{document}) tetraquarks with strange flavor in the chiral quark model. Two pictures, one with meson-meson picture, another with diquark-antidiquark picture and their couplings are considered in our calculations. Isospin violation is neglected herein. Our numerical analysis indicates that the states \begin{document}$ cc\bar{u}\bar{s} $\end{document} with \begin{document}$ \dfrac{1}{2}(1^+) $\end{document} and \begin{document}$ bb\bar{u}\bar{s} $\end{document} with \begin{document}$ \dfrac{1}{2}(1^+) $\end{document} are the most promising stable states against strong interactions. Besides, we also find several resonance states for the double-heavy strange tetraquarks with the real scaling method.
Observations of the Cabibbo-Suppressed decays ${\boldsymbol \Lambda_{\boldsymbol c}^{\bf +}\to\boldsymbol n\pi^{\bf +}\boldsymbol\pi^{\bf 0}} $, ${\boldsymbol n\pi^{+}\boldsymbol\pi^{\bf -}\boldsymbol\pi^{\bf +} }$ and the Cabibbo-Favored decay ${\boldsymbol \Lambda_{\boldsymbol c}^{\bf +}\to \boldsymbol nK^{\bf -}\boldsymbol\pi^{\bf +}\boldsymbol\pi^{\bf +} }$
M. Ablikim, M. N. Achasov, P. Adlarson, M. Albrecht, R. Aliberti, A. Amoroso, M. R. An, Q. An, Y. Bai, O. Bakina, R. Baldini Ferroli, I. Balossino, Y. Ban, V. Batozskaya, D. Becker, K. Begzsuren, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, J. Bloms, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, J. F. Chang, W. L. Chang, G. R. Che, G. Chelkov, C. Chen, Chao Chen, G. Chen, H. S. Chen, M. L. Chen, S. J. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Z. J. Chen, W. S. Cheng, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, S. X. Du, Z. H. Duan, P. Egorov, Y. L. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, K Fischer, M. Fritsch, C. Fritzsch, C. D. Fu, H. Gao, Y. N.
Published:   , doi: 10.1088/1674-1137/ac9d29
Abstract:
Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb\begin{document}$ ^{-1} $\end{document}, collected by the BESIII detector in the energy region between \begin{document}$ 4599.53\; \,{\rm{MeV}} $\end{document} and \begin{document}$ 4698.82\; \,{\rm{MeV}} $\end{document}, we report the first observations of the Cabibbo-suppressed decays \begin{document}$ \Lambda_c^+\to n\pi^+\pi^0 $\end{document}, \begin{document}$ \Lambda_c^+\to n\pi^+\pi^-\pi^+ $\end{document}, and the Cabibbo-favored decay \begin{document}$ \Lambda_c^+\to nK^-\pi^+\pi^+ $\end{document} with statistical significances of \begin{document}$ 7.9\sigma $\end{document}, \begin{document}$ 7.8\sigma $\end{document}, and \begin{document}$ >10\sigma $\end{document}, respectively. The branching fractions of these decays are measured to be \begin{document}$ \mathcal{B}(\Lambda_{c}^{+}\rightarrow n\pi^{+}\pi^{0})=(0.64\pm0.09\pm0.02)\ $\end{document}%, \begin{document}$ \mathcal{B}(\Lambda_{c}^{+}\rightarrow n\pi^{+}\pi^{-}\pi^{+})=(0.45\pm $\end{document}\begin{document}$ 0.07\pm0.03)\ $\end{document}%, and \begin{document}$ \mathcal{B}(\Lambda_{c}^{+}\rightarrow nK^{-}\pi^{+}\pi^{+})=(1.90\pm0.08\pm0.09)\ $\end{document}%, where the first uncertainties are statistical and the second are systematic. We find that the branching fraction of the decay \begin{document}$ \Lambda_{c}^{+}\rightarrow n\pi^{+}\pi^{0} $\end{document} is about one order of magnitude higher than that of \begin{document}$ \Lambda_{c}^{+}\rightarrow n\pi^{+} $\end{document}.
Maximum mass of anisotropic charged strange quark star in higher dimensional approach (D ≥ 4)
A. Saha, K.B. Goswamiy, B. Dasz, P.K. Chattopadhyayx
Published:  
Abstract:
In this article, a new class of solutions of Einstein-Maxwell field equations of relativistic strange quark star obtained in dimensions \begin{document}$D\geq4$\end{document}, is shown. We assumed the geometry of space-time to be pseudo-spheroid, embedded in Euclidean space of \begin{document}$(D-1)$\end{document} dimensions. MIT bag model equation of state \begin{document}$(henceforth~EoS)$\end{document} is employed to study the relevant properties of strange quark star. For causal and non-negative nature of the square of radial sound velocity \begin{document}$({v_{r}}^{2})$\end{document}, it is found that some restrictions on the reduced radius \begin{document}$(\frac{b}{R})$\end{document} exist, where R is termed as a parameter related to curvature of the space-time and b is the radius of the star. Spheroidal parameter λ used here is to define metric potential of the \begin{document}$g_{rr}$\end{document} component which is pseudo-spheroidal in nature. We note that pressure anisotropy and charge have some effects on λ. The maximum mass for a given surface density (\begin{document}$\rho_s$\end{document}) or bag constant \begin{document}$(B)$\end{document} assumes a maximum value in dimension \begin{document}$D=5$\end{document} and decreases for other values of D. The generalized Buchdahl limit for a higher dimensional charged star is also obeyed in this model. It is found that in this model, one can predict the mass of a strange quark star using suitable value of electric charge (Q) and bag constant (B). Energy and stability conditions are also satisfied in the present model. Stability is also studied considering the dependence of the Lagrangian perturbation of radial pressure (\begin{document}$\Delta p_r$\end{document}) on frequency of normal modes of oscillations. Tidal love number and tidal de-formability are also evaluated.
Binding energies of proton-rich nuclei determined from their mirror pairs
Shuai Liu, Hao-Kang Jia, Teng-Fei Wang, Yi-Bin Qian
Published:   , doi: 10.1088/1674-1137/ac9893
Abstract:
Besides the Coulomb displacement energy, the residual differences of binding energies between mirror nuclei (a pair of nuclei with the same mass number plus the interchanged proton and neutron numbers) are contributed to the shell effect via the valence scheme in the present study. To this end, one linear combining type of the valence nucleon number, namely \begin{document}$ \alpha N_p+\beta N_n $\end{document}, is chosen to tackle this shell correction, in which \begin{document}$ N_p $\end{document} and \begin{document}$ N_n $\end{document} are separately the valence proton and neutron numbers with respect to the nearest shell closure. The mass differences of mirror nuclei, as the sum of the empirical Coulomb displacement energy and the shell effect correction, are then used to obtain the binding energies of proton-rich nuclei through the available data of their mirror partners, in order to be useful for exploring the proton dripline of nuclear chart.
Search for the weak decay ${\boldsymbol \psi(3686) \boldsymbol\to \boldsymbol\Lambda_c^{+} \bar{\Sigma}^- +c.c.} $
M. Ablikim, M. N. Achasov, P. Adlarson, M. Albrecht, R. Aliberti, A. Amoroso, M. R. An, Q. An, X. H. Bai, Y. Bai, O. Bakina, R. Baldini Ferroli, I. Balossino, Y. Ban, V. Batozskaya, D. Becker, K. Begzsuren, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, J. Bloms, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, J. F. Chang, W. L. Chang, G. Chelkov, C. Chen, Chao Chen, G. Chen, H. S. Chen, M. L. Chen, S. J. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Z. J. Chen, W. S. Cheng, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, S. X. Du, P. Egorov, Y. L. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, K Fischer, M. Fritsch, C. Fritzsch, C. D. Fu, H. Gao, Y. N. Gao, Yang Gao, S. Garbolino, I. Ga
Published:   , doi: 10.1088/1674-1137/ac9895
Abstract:
Using \begin{document}$ (448.1 \pm 2.9) \times 10^{6} $\end{document} \begin{document}$ \psi(3686) $\end{document} events collected with the BESIII detector, we perform the first search for the weak baryonic decay \begin{document}$ \psi(3686) \to \Lambda_c^{+} \bar{\Sigma}^- +c.c. $\end{document}. The analysis procedure is optimized using a blinded method. No significant signal is observed, and the upper limit on the branching fraction (\begin{document}$ \mathcal B $\end{document}) of \begin{document}$ \psi(3686) \to \Lambda_c^{+} \bar{\Sigma}^- +c.c. $\end{document} is set to be \begin{document}$ 1.4\times 10^{-5} $\end{document} at the 90% confidence level.
Three-quark potential at finite temperature and chemical potential
Jia-Jie Jiang, Ya-Zhao Xiao, Jiajia Qin, Xiaohua Li, Xun Chen
Published:   , doi: 10.1088/1674-1137/ac9894
Abstract:
Using gauge/gravity duality, we study the potential energy and the melting of triply heavy baryon at finite temperature and chemical potential in this paper. First, we calculate three-quark potential and compare the results with quark-antiquark potential. With the increase of temperature and chemical potential, the potential energy will decrease at large distances. It is found that the three-quark potential will have an endpoint at high temperature and/or large chemical potential, which means triply heavy baryons will melt at enough high temperature and/or large chemical potential. We also discuss screening distance which can be extracted from the three-quark potential. At last, we draw the melting diagram of triply heavy baryons in the \begin{document}$ T-\mu $\end{document} plane.
Search for Majoron at the COMET Experiment
Tianyu Xing, Chen Wu, Han Miao, Haibo Li, Weiguo Li, Ye Yuan, Yao Zhang
Published:   , doi: 10.1088/1674-1137/ac9897
Abstract:
A new Goldstone particle named Majoron is introduced in order to explain the origin of neutrino mass by some new physics models assuming that neutrinos are Majorana particle. By expanding signal region and using likelihood analysis, it becomes possible to search for Majoron at experiments that is originally designed to search for \begin{document}$ \mu-e $\end{document} conversion. For the COMET experiment, the sensitivity of process \begin{document}$ \mu \rightarrow eJ $\end{document} is able to reach \begin{document}$ {\cal{B}}(\mu \rightarrow eJ)=2.3\times 10^{-5} $\end{document} in Phase-I and \begin{document}$ O(10^{-8}) $\end{document} in Phase-II. Meanwhile, the sensitivities to search for Majoron at future experiments are also discussed in this article.